OF ARTS AND SCIENCES. 103 



Examined with the eye, the kephir-grains when fresh are found to 

 consist of white, conipact, elastic masses, enveloped by a slime, and 

 with a spherical or elliptical contour, varying from 1 mm. to 5 cm. 

 in diameter. The very small grains have a smooth spherical exterior, 

 while the larger ones are provided with outgrowths and furrows, look- 

 ing more or less like a very small cauliliower. When the grains are 

 dried they assume a yellowish brown color, and shrink a good deal 

 by the loss of water. When examined with the microscope there 

 are found in each grain, whatever its form or size, two different 

 structures, yeast cells and Bacteria, The latter form the mass of the 

 grain in which the yeast cells are embedded. 



The yeast cells occur in pairs or rows of cells of all shapes and 

 sizes. Most of them are elliptical or spherical, the former varying 

 from 3.2 /x to 9.6 /x, by 3.2 jx to 6.4 ju, the spherical ones varying from 

 3.2 /A to 6.4 /x in diameter. Each yeast cell has a plainly visible mem- 

 brane with a double contour, brought out by stains. Within the cell 

 is a vacuole, at the poles of which are often found small fat globules 

 in no definite number, but which increase in number as the cell is 

 dried, the protoplasm at the same time becoming granular, the vacu- 

 oles diminishing in size and ultimately disappearing. The yeast cells 

 increase by budding. 



Kern discusses the question of the possibility that the yeast cells 

 may be the spores of some Mucor, as 3f. racemosus for example, since 

 these are known to cause alcoholic fermentation ; but since cultures 

 continued for weeks failed to show him a trace of mycelium, he con- 

 cludes that there can be no doubt that these are true yeast cells. 



The origin of the kephir grains was unknown to Kern. He could 

 find no wild form of yeast from which they might have been culti- 

 vated ; nor could he gather any information as to their source from 

 the peasants. They are said to grow in little clumps or granules on 

 peculiar bushes found on the mountains just beneath the snow line. 



Kern could not induce the kephir yeast to form spores. He ex- 

 plains the matter by saying that these yeast cells have for an infinity 

 of generations grown in milk only, and have increased only by bud- 

 ding. Hence, when they are exposed to conditions favorable for 

 spore formation, they are unable to form spores. He declares the 

 kephir yeast to be ordinary Sacchnromyces cerevisice, Meyen, saying 

 that he cannot agree with Dr. Max Reess in classifying yeasts accord- 

 ing to their form and size. The form and size of the cells vary too 

 much ; besides, the variations are not constant, being conditioned 

 partly by age, partly by the nature of the nourishing medium, and 

 partly by the temperature. 



